The production of flat sheet glass by the float glass process involves the pouring of molten glass onto a bath of molten tin within a float glass furnace. To prevent the surface of the hot tin from oxidizing, an atmosphere of nitrogen is used in the float glass furnace. The atmosphere also contains hydrogen which reacts with any oxygen which is present to form water vapor, and with sulfur generated from the glass to form hydrogen sulfide. This further ensures the integrity of the hot tin and the molten glass within the furnace. Some stannous sulfide and stannous oxide may be produced which volatize and may condense on the roof of the furnace.
The protective atmosphere within the float glass furnace will become contaminated and will no longer be effective. To overcome this problem, it is conventional practice in the float glass industry to purge the float glass furnace of the contaminated protective atmosphere and replace it with a clean atmosphere of nitrogen and hydrogen. The purge may be intermittent or continuous. A continuous purge, although more costly, is preferred because it enables the production of better quality glass.
The purge of the contaminated protective atmosphere from a float glass furnace and its replacement with a new atmosphere is costly.
Accordingly, it is an object of this invention to provide a system which will reduce the costs of manufacturing glass using the float glass method while not compromising the quality of the manufactured glass.